"It's the nature of user-generated content," she said in a call following news of the deal.

She also said that Tumblr would continue to utilise its 'NSFW' and 'Adult' labels, to prevent users from seeing content they'd prefer not to see.

"It's really important to have great community tools like 'NSFW' that Tumblr already has in place," she said.

Her comments echo Yahoo's promise to run Tumblr as a "separate company" and "not to screw it up".

Mayer said in a statement yesterday:

"On many levels, Tumblr and Yahoo! couldn't be more different, but, at the same time, they couldn't be more complementary. Yahoo is the Internet's original media network. Tumblr is the Internet's fastest-growing media frenzy.
"Both companies are homes for brands - established and emerging. And, fundamentally, Tumblr and Yahoo! are both all about users, design, and finding surprise and inspiration amidst the everyday."